The invention relates to a multi-speed gear hub, e.g., for bicycles.
A multi-speed gear hub disclosed in Austrian Patent Document 165,740 includes two claw clutches which are successively actuable by a single gearshift linkage part (connecting rod 36). From the initial gearshift position of the connecting rod, the (first) claw clutch nearest the driver gear wheel 41 is actuated first, the projecting claw part (gearshift sleeve 40) being movable from a first gearshift position with rotationally fixed connection between driver gear wheel and planet wheel carrier 17 into a second gearshift position with rotationally fixed connection between driver gear wheel and ring gear 11 and with active overriding clutch 12 between ring gear 11 and hub sleeve 33, and being movable further into a third gearshift position in which the driver gear wheel remains coupled with the ring gear, but in which the overriding clutch is inactive. This gearshift movement is effected against the force of a first preloading spring 38. In the three gearshift positions, the projecting claw part (sleeve 51) of the second claw clutch remains in its current gearshift position, in which it couples a sun wheel 25 of a supplemental planetary gear rotationally fixed with the hub shaft. This is possible as the associated driving member 54, which is rigidly connected with the connecting rod, engages the projecting claw part 51 for driving with a driving shoulder 54c only when the third gearshift position of the connecting rod is reached. A first preloading spring 57 preloads the projecting claw part into this gearshift position. If the connecting rod 36 is pulled further, the shoulder 54c drives the projecting claw part into an additional gearshift position in which the claw part releases the sun wheel of the supplemental planetary gear, and fixes a part 22 rotationally fixed on the hub shaft. Part 22 bears the sun wheels for the main planetary gear and also serves as planet wheel carrier for the supplemental planetary gear. To permit this connecting-rod movement while the projecting claw part (gearshift sleeve 40) of the first clutch is stationary, the projecting claw part is not rigidly fixed to the connecting rod, but is movable on the rod against the force of a spring 56 which suitably preloads the projecting claw part for abutment against the end of the connecting rod 36. The opposite end of this spring is supported on an annular shoulder of the driving member 54 which is screwed into a threaded opening of the connecting rod 36. The preloading force of the spring 56 is less than that of the first preloading spring 38.
This construction provides for the two clutches to be actuable successively by a single, tension-loaded gearshift linkage part. When the planetary gear is stationary, i.e., during standing or riding without pedaling, through-shifting by pulling out of the connecting rod into the end gearshift position opposite the initial gearshift position is reliably possible only when the counterprojecting claw parts 50, 53 are oriented alike, so that the projecting claw part 51 can be shifted axially between the two parts without difficulty.
Similarly, through-shifting is not possible in a multi-speed gear hub with a single connecting rod as represented in FIG. 1 of German Patent Document 814,982. This applies also to the embodiments according to FIGS. 4 and 5 of German Patent Document 814,982, as there the projecting claw parts are rigidly connected with the respective gearshift linkage part. Free through-shifting is precluded also in the multi-speed gear hubs with two claw clutches (5-speed hub) disclosed in British Patent Document 2,166,502, as in this case the pressure-loaded gearshift linkage parts directly abut the corresponding projecting claw parts. When shifting during standstill of the planetary gear upon actuation of the gearshift means, as the gearshift linkage parts are moved further into the hub against the force of first preloading springs, the movement of the gearshift linkage part is momentarily blocked unless the angles of corresponding projecting claws or counterprojecting claws happen to match.